1. McDonald's started testing garlic fries, and quickly sold out of them.

The chain starting testing the fries at four locations in San Francisco earlier this year.

Within a matter of days after launching them, the restaurants sold out of the new menu item, according to SFGate.

"In less than two weeks, our small, four-restaurant test of Gilroy Garlic Fries has been a huge success, and we are now experiencing a temporary shortage of supplies," McDonald's told SFGate. "We are excited about how many people have visited our restaurants to try the fries, and we apologize for any inconvenience to our customers."

The fried potatoes are seasoned with garlic grown in Gilroy, California — a place known as "the garlic capital of the world," according to McDonald's.

The made-to-order fries are tossed with a purée mix of "Gilroy garlic and olive oil, parmesan cheese, parsley, and a pinch of salt," the company says.

McDonald's has long relied on an extensive network of suppliers who make, freeze, and ship beef patties to its more than 14,000 restaurants in the US.

Expanding the fresh beef test would require big changes to its supply chain.

McDonald's CEO Steve Easterbrook said last month that there isn't currently a large enough supply of fresh beef to expand the test nationally, but that the company could start expanding it gradually region by region.

"Would that supply be there right now? No it wouldn't," Easterbrook said at a conference in New York. "It doesn't mean we shouldn't start to expand it. You can go region by region ... and develop it that way. We are pretty good at solving operational supply chain issues when we have a good idea."

4. To great fanfare, it launched an all-day breakfast menu.

Getty Images/Justin Sullivan

The all-day breakfast menu was rolled out in October, and McDonald's has credited it for driving recent sales growth.

Customers long begged McDonald's to make its breakfast menu available all day.

Since the launch, customers have been ordering breakfast-menu items on the side with their meals during lunch and dinner hours, driving up ticket prices during those times, McDonald's CEO Steve Easterbrook said earlier this year.

5. A chicken Caesar sandwich was launched in the New York tri-state area.

10. The chain also stopped using margarine on its breakfast sandwiches and replaced it with real butter.

Adding butter had an immediate impact, driving up sales of Egg McMuffins by double digits, executives said last year.

In addition to the McMuffins, executives said another butter-based recipe also helped drive McDonald's sales in the most recent quarter: the buttermilk crispy sandwich.

"It outperformed the high end of our expectations," McDonald's CEO Steve Easterbrook said of the sandwich.

11. McDonald's tried to please budget-conscious customers with a new promotion, called McPick 2.

Reuters

McDonald's introduced McPick 2 in January. It let customers select two of the following items for $2: a McDouble, a McChicken, small fries, and mozzarella sticks.

In late February, McDonald's raised the price of the promotion to $5. The new menu let customers select two of the following for $5: a Big Mac, 10-piece chicken McNuggets, a Filet-O-Fish sandwich, and a Quarter Pounder with cheese.

The burger chain upset many customers two years ago when it reformulated the Dollar Menu by axing the $1 price ceiling and turning it into the "Dollar Menu & More" with items that cost up to $5.

"Some of the challenges we've had in the US have been somewhat self-inflicted," Easterbrook said during a conference call last summer. "We moved away from the Dollar Menu and didn't replace it with significant-enough value in the eyes of consumers."

12. And the company didn't stop experimenting with more indulgent foods. McDonald's launched a crispy buttermilk sandwich nationwide last August.

McDonald's

The company says the buttermilk crispy chicken sandwich has been a hit.

"It outperformed the high end of our expectations," Easterbrook said of the sandwich during an earnings call last fall.

McDonald's also started testing a new ground-chicken burger.

The ground chicken burger is made from a blend of white and dark ground chicken seasoned with spices like garlic and onion powder. It can be ordered in two varieties: "Classic," with red onions and ranch sauce; and "tangy," with grilled onions and a tangy "signature sauce."

The sandwich was tested in McDonald's Tampa locations.

13. McDonald's started expanding its customizable-burger menu, called "Create Your Taste," to thousands of restaurants nationwide.

Hollis Johnson

The menu allows people to customize their burgers with premium toppings like guacamole, grilled mushrooms, onions, bacon, and chili-lime tortilla strips, using touch-screen kiosks.

The chain is also now offering a limited version of "Create Your Taste" to drive-thru customers called "TasteCrafted," where people can pick a bun and a premium sauce.

14. The company reintroduced Premium Chicken Selects, which cost $2.99 for a three-piece order, compared with $1.99 for a four-piece Chicken McNugget order.

15. McDonald's tested a premium sirloin burger, but decided to phase it out when it didn't meet sales expectations.

The burgers, made with 100% sirloin, featured the biggest meat patties on McDonald's menu. They were served on wooden boards meant to signify their premium quality, along with fancy toppings like grilled mushrooms, white cheddar cheese, and peppercorn sauce.

16. McDonald's launched mozzarella sticks nationwide.

Hollis Johnson

The snack was added as part of the McPick promotion, which allowed customers to pick two of the following for $2: a McDouble, a McChicken, small fries, and mozzarella sticks.

The mozzarella sticks are also available on their own, costing$1 for three sticks.